This invention relates to an electrophotosensitive member.
The electrophotosensitive member takes various constructions for obtaining predetermined characteristics, or in accordance with kinds of the electrophotographic process to be adopted. As the representative example of the electrophotosensitive member, there is such one that has a photoconductive layer formed on a base member (or a substrate), and such other one that has an insulative layer provided on the surface of the photoconductive layer. These electrophotosensitive members are widely used. The photosensitive member constructed with the substrate and the photoconductive layer is used in the image formation by the most general electrophotographic process, i.e., the image formation by electric charging, imagewise exposure, development, and further, image transfer, depending on necessity. In the photosensitive member having the insulating layer, this insulating layer is for various purposes such as protection of the photoconductive layer, improvement in the mechanical strength of the photosensitive member, improvement in the dark decay characteristics, adaptation of the photosensitive member to a particular electrophotographic process, and various others. Representative examples of the electrophotographic process using the photosensitive member having the insulating layer or the photosensitive member having such insulating member are: U.S. Pat. No. 2,860,048, Japanese Patent Publication No. Sho 41-16429, Japanese Patent Publication No. Sho 38-15446 (corresponding to U.S. Pat. No. 3,146,145), Japanese Patent Publication No. Sho 46-3713 (corresponding to U.S. Pat. No. 3,607,258), Japanese Patent Publication No. Sho 42-23910 (corresponding to U.S. Pat. No. 3,666,363), Japanese Patent Publication No. Sho 43-24748 (corresponding to U.S. Pat. No. 3,734,609), Japanese Patent Publication No. Sho 42-19747 (corresponding to U.S. Pat. No. 3,457,070), Japanese Patent Publication No. Sho 36-4121 (corresponding to U.S. Pat. No. 3,124,456), and others.
The electrophotosensitive member is required, as a matter of course, to have a predetermined sensitivity in accordance with the electrophotographic process to be adopted. The moisture-resistant property of the photoconductive layer is one of the important characteristics of such electrophotosensitive member. In particular, when the photoconductive layer consists of a photoconductive material dispersed in a binding resin, there tends to readily occur deterioration in the electrical charging in connection with moisture.
There has so far been attempted to improve the photoconductive powder with respect to its moisture-resistant property by, for example, controlling a quantity of impurities, or controlling the particle diameter and the shape of powder particles due to the calcining temperature, or selecting the king of resin to be used as the binding resin.